Protein Synthesis in Imbibed Seeds III. Kinetics of Amino Acid Incorporation Ribosome Activation, and Polysome Formation.

The kinetics of development of protein-synthesizing capacity in the imbibing wheat embryo, were studied both in vivo and in vitro. During the first 30 minutes of imbibition protein-synthesizing capacity rises rapidly, lagging about 10 minutes behind water uptake. This rise in synthesizing capacity is accompanied by an increase in polysome content. As imbibition continues, both protein-synthesizing capacity and polysome content increase. With embryos from aged seed, the rate of protein synthesis is initially limited by another, presumably nonribosomal, reaction.